Structure for cone and periscope of spiral path scanning mechanism

ABSTRACT

A scanner for bubble chamber photographs comprises a rotatable mirror-carrying outer member and an inner periscope member that rotates with and moves lengthwise relative to the outer member. The periscope member has accurately straight track surfaces along its length that parallel the rotational axis and lie in substantially perpendicular planes which respectively extend to opposite sides of said axis. Each of said tracks is engaged by rollers carried by the outer member at fixed axially spaced locations. Other rollers on the outer member engage the periscope member under radially inward bias to maintain the track surfaces guidingly engaged with the first mentioned rollers.

V 1141; References Cited [72] Inventors V l Mandi; Laxaqzeim 1 1 Li /WEDSTATES PATENTS i/F -1' I Spear 350/52 [211 P 2 3 11. Howell 350/7 [221PM 2,418,799 4/1947 Willard..... 350/84 1451 $301197! 3,207,034 9/1965Harter 350/52 [731 i fi tg fg fi 3,450,481 6/1969 Kramp et al.. 350/6)([32] Priority g 8 1968 3,021,010 1/1969 Toby 178/76X [33] Sweden PrzmaryExammer Davld Schonberg 1 1 11,530 d 1153] Assistant Examiner-Paul R.Mlller Altorney--lra Milton Jones ABSTRACT: A scanner for bubble chamberphotographs comprises a rotatable mirror-carrying outer member and aninner @665; member that rotates with and moves [54] lengthwise relativeto the outer member. The periscope 9 Cl 6 D member has accuratelystraight track surfaces along its length rawmg that parallel therotational axis and lie in substantially perpen- [52] US. Cl 350/6,dicular planes which respectively extend to opposite sides of 178/7.6,250/236, 350/7, 350/285 said axisv Each of said tracks is engaged byrollers carried by [51] Int. Cl 6021) 17/00 the outer member at fixedaxially spaced locations. Other rol- [50] Field of Search 350/6, 7, lerson the outer member engage the periscope member under 250/81-85, 235237;178/76; radially inward bias to maintain the track surfaces guidingly74/3 (C) engaged with the first mentioned rollers.

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STRUCTURE FOR CONE AND PERISCOPE OF SPIRAL PATH SCANNING MECHANISM Thisinvention relates generally to apparatus for scanning photographs of thetracks made by charged particles in a bubble chamber or cloud chamberfor the purpose of converting the records contained on such photographsto a form that can be used by a computer and ultimately analyzed toprovide information about particle interactions and decays in nuclearphysics experiments; and the invention relates more particularly to aso-called spiral reader for such photographs. comprising a mirror whichmoves orbitally about an axis at a substantially high speed, and aperiscope which is caused to move parallel to the same axis whilerotating with the mirror about that axis. The invention relates,specifically, to structure by which the mirror and periscope areconstrained precisely to the motions desired for them.

A bubble or cloud chamber, containing fluid in a condition ofequilibrium between the liquid and gaseous states and surrounded by asuperconductive electromagnet, is a well-known device used in nuclearphysics experiments. When a charged particle is shot into the chamber,it leaves a track of tiny bubbles; and when it encounters anotherparticle (which encounter is called an event") the particles taking partin the event trace branching tracks which diverge from the point of theencounter. These bubble tracks, although persisting only very briefly (amatter of microseconds) can be photographed stereoscopically to providea record of the several paths taken by the particles involved in eachevent. Since the motions of the particles provide a clue to theirnatures, the study of photographic records of the branching or divergingtracks that denote events is of particular interest.

A reading machine of the type to which this invention relates is used toscan bubble chamber photographs for the purpose of converting thepictorial records of events to a form of data that can be stored in andused by an electronic computer. When a sufficient amount of such data isavailable, derived from the photographic records of numerousexperiments, con clusions can be drawn, on the basis of statisticalanalysis of the data, about the nature and characteristics of theparticles involved in the events being studied.

Inasmuch as valid conclusions can be drawn only on the basis ofstatistical study of a very large number of experiments, a tremendousamount of film needs to be analyzed- -truckloads, in many cases.Automation of the reading" of the film records is therefore essential toreasonable management and utilization of the data contained in suchrecords.

Each frame of film to be analyzed may contain one or more sets ofdiverging tracks that signify events, along with numerous other linesthat trace the paths of particles that did not take part in events andwhich are therefore not of interest.

Selection of each part of a frame of film to be scanned is accomplished,at least in part, with the aid of a human operator. As it scans theimage on the film, the automatic reader produces signals correspondingto all tracks on the portion of the film being scanned. These signalsare fed to a computer which in effect rejects signals corresponding totracks not of interest and preserves data relating to events selectedfor analysis.

This invention is based upon the premise that the nature of the tracksto be analyzed is such that the most efficient and useful pattern ofscanning is a spiral one in which the origin of the spiral is at thepoint where several diverging tracks have their junction or vertex thatdenotes an event.

in a very general way it is an object of the present invention toprovide mechanical means for effecting scanning in a spiral scanningpath of film records of the character described, which scanning meanscomprises a mirror that rotates about a fixed axisandis-so inclined tosaid axis as to generate a cone in the course of its rotation, and aperiscope having an optical element or eye that faces the mirror androtates therewith and at the same time moves steadily along the axisabout which the mirror rotates.

To be practical for the scientific purpose for which it is intended, ascanning mechanism of the character just described must rotate at arelatively high speed, in order to accomplish its work expeditiously(bearing in mind the tremendous volume of records to be processed); butit must nevertheless embody a very high degree of precision so that thedata obtained from each reading will accurately portray the recordedevent being read.

lt is therefore another object of this invention to provide means forconstraining the mirror and periscope in a spiral reader of thecharacter described to exactly the motions prescribed for them so thatthey remain uninfluenced by centrifugal and other forces which act uponthem and which tend to divert them from the desired motions.

With these observations and objects in mind, the manner in which theinvention achieves its purpose will be appreciated from the followingdescription and the accompanying drawings. This disclosure is intendedmerely to exemplify the invention. The invention is not limited to theparticular structure disclosed, and changes can be made therein whichlie within the scope of the appended claims without departing from theinvention.

The drawings illustrate one complete example of a physical embodiment ofthe invention constructed according to the best mode so far devised forthe practical application of the principles thereof, and in which:

FIG. 1 is a general perspective view of reading apparatus embodying theprinciples of this invention, shown in operative relation to otherapparatus with which it cooperates;

FIG. 2 is a vertical sectional view through spiral scanning apparatusembodying this invention;

FIG. 3 is a horizontal sectional view taken on the plane of the line 3-3in HG. 2;

FIG. 4 is a fragmentary view, partly in perspective and partly insection, showing the structure by which the periscope member isconstrained to rotate with the mirror carrying member and to move up anddown relative to the mirror carrying member, exactly parallel to theaxis of rotation thereof. the view being taken generally near the top ofthe mirror carrying member;

FIG. 5 is a fragmentary sectional view taken on the plane of the line5-5 in FIG. 3; and

FIG. 6 is a fragmentary sectional view taken on the plane of the line6-6 in FIG. 5.

Referring now more particularly to the accompanying drawings, thenumeral 4 designates generally a reading machine in which the presentinvention is embodied, and FIG. 1 illustrates it in its relationship toapparatus with which it cooperates.

The film to be analyzed or read by means of the reading machine 4 is inthe form of long strips, each divided along its length into a number offrames, and each frame usually containing a record of one or more eventswhich are of interest. To facilitate handling, each strip is normallywound onto a reel to form a roll. Inasmuch as each experiment in abubble chamber is photographed simultaneously by three cameras, focusedalong coordinate axes, three related rolls of film must be read more orless simultaneously, to coordinate data for each frame in each roll withthat for the corresponding frames in the other two rolls. The frames ineach roll are successively numbered before the film is presented to thereading machine 4, to facilitate identification of the recorded events.

In FIG. 1, three related strips of film to be scanned by the readingmachine are respectively designated 5, 6 and 7. The extend across ahorizontal table 8 on the reading machine having three apertures, onefor each roll, that are aligned with a suitable light source (not shown)which is located beneath the table. Film transport means, comprising asuitable capstan drive 9, provides for advancing the rolls of filmsimultaneously across the table 8, to permit successive frames on eachroll to be brought into register with the apertures in the table for thepurpose of scanning. in addition, the film table is capable of bodilymovement in all horizontal directions to permit any selected portion ofa frame of film to be brought into alignement with the axis of anobjective head which is fixed above the film table and which comprisesreflecting means. A companion application, Ser. No. 854,147, filed Aug.28, 1969, discloses means for constraining the film take up and supplyreels to move horizontally with the table, to avoid twisting distortionof the film.

The image on the film frame that is under the objective head isprojected up into the objective head, thence horizontally in onedirection, and finally down onto the top surface of an operators table11. An obliquely disposed mirror 12 above the operators table receivesthe image from the objective head and reflects it downwardly onto theoperators table.

The image is also projected from the objective head in the oppositehorizontal direction, toward a half-silvered mirror 13, whence it isreflected downwardly into scanning mechanism 14 which is describedhereinafter. The image is also projected through the half-silveredmirror into a television camera 15 which receives only a very smallportion of the total image on a film frame, corresponding to about asquare millimeter of the film around the axis of the objective head. Theimage of this small area is presented to the operator, in very greatlymagnified form, on the screen of a television camera. This highlymagnified portion of the total image is used for accurately locating thefilm table to bring the vertex of the event record to be studied intoexact coincidence with the axis of the objective head and hence intocoincidence with the scanning axis of the scanning device 14.

On the operators table there is a control console 17 for controllingfilm advance and the horizontal movements of the film table. Theoperator also has a typewriter 19 for input and output of data and anoscilloscope 20 that gives a graphic representation of light valuesmeasured during scanning.

The scanning device 14 is connected with an electronic computer 21through an adapter 22 which is in itself a form of electronic computer.

Before a set of films is actually scanned or read, it is prescanned tostore in the computing apparatus the numbers of those frames that recordevents of interest and the approximate locations on the frames of thevertices of such events. For the actual scanning operation, the computerso controls the film transport that each in turn of the frames to bestudied is brought into register with the apertures in the film table.When a frame has thus been advanced into and locked in the film table,the computer makes a rough adjustment of the table, based on dataobtained in the prescanning, and the operator makes the final adjustmentby reference to the television receiver 16. After the first frame isread, the computer automatically shifts the table to properly align thevertices on the corresponding frames of the other two rolls of film.

Because film is dimensionally unstable, each frame of film has spacedapart fiducial marks, corresponding to fixed points in the photographedbubble chamber, and an accurate measurement of the distances betweenfiducial marks on a frame provides scale data for it from which eventsrecorded thereon can be accurately located in the bubble chamber space.For feeding data into the computer concerning the coordinates of thefiducial marks on each frame, there is a fiducial plate 23 in front ofthe television camera that has specially shaped slots, andphotomultipliers behind the slots register when the images of thefiducial marks align with these slots as the film table moves a framehorizontally. The signals from the photomultipliers are combined withinformation derived from the table movements to produce informationconcerning the scale of the frame, which information is stored in thecomputer and used in conjunction with the signals obtained from thescanning of particle tracks that are recorded on the film.

Scanning can begin as soon as the vertex of an event record to bestudied has been brought into coincidence with the optical axis.

The image of an event on a film frame is scanned in a spiral path, andhence the scanning apparatus is known as a spiral reader. The scanningbegins at the vertex, progressing outwardly and around, and a signal isproduced each time a track on the film record is crossed in the courseof such scanning. Since data concerning the radial and angularcoordinates of the scan are continuously fed to the computer, thescanning process results in the storing of data which characterizes theevent. After the record of a selected event on a frame of film has beenscanned, records of the same event on the counterpart frames of theother two rolls of film are similarly scanned, the vertices of the othertwo records being automatically located by the computer and aligned withthe scanning axis. Data from the three scannings of the event arecombined by the computer into a form that defines an unambiguous threedimensional curve which characterizes the event, and this is stored inthe computer to be available for comparison with similarly obtained datafor other events, for the purposes of statistical analysis.

The scanning device 14 by which the photographed image of an event isscanned along the desired spiral path comprises, in general,concentrically arranged inner and outer members 25 and 26. The outermember 26 carries a plane mirror 27 and is constrained to rotation on afixed axis. The inner member 25 comprises a periscope and is constrainedto both rotation with the outer member and motion relative to it indirections accurately parallel to said fixed axis.

The axis about which the mirror carrying outer member 26 rotates can beconsidered to coincide with the vertex of an event to be scanned; or,more a accurately, when the film table 8 has been accurately located todispose a film frame for scanning, the image of the vertex of the eventto be scanned is projected exactly along the axis of the outer member,as represented by the broken line 28 in FIG. 1.

The outer member comprises a generally funnel shaped body 29, as seen inFIG. 2, and the which is elongated and generally rectanglmfis'secured ina groove in the inner surface of the conical upper portion of that body.The mirror extends lengthwise in the direction radial to the rotationalaxis (as best seen in FIG. 3) and it is disposed obliquely to that axis,being inclined, along its length, radially outwardly and upwardly (asshown in FIG/2), so that it reflects inwardly toward the axis an imageprojected down onto it parallel to the axis. Thus as the mirror iscarried orbitally in consequence of rotation of the outer member, itdefines a reflecting cone and scans a circular area of the film framethat has at its center a vertex denoting an event. At every instantduring such scan the mirror reflects toward the axis a striplikeradially extending portion of that circular area. Note that the bottomportion of the mirror extends across the rotational axis, so that thestrip reflected by the mirror will always include the vertex of theevent.

As the inner periscope member 25 rotates with the mirror, its eye alwaysfaces the mirror. Hence, as the periscope moves upwardly parallel to theaxis of rotation, it scans along the strip being scanned by the mirror.And since that strip is moving angularly around the vertex at a steadyrate, and the periscope is scanning at a steady rate along that strip,the net effect of the combined scanning motions is the desired spiralscan. A companion application, Ser. No. 853,830, filed Aug.

28, [969, discloses means for adjustably masking the periscope eye forvarying the area of the mirrored image that the periscope scans.

The embodiment of the mirror and periscope scanning principle intoactual apparatus has involved certain complex problems. The changes inlight value picked up by the periscope eye in the course of its scanmust be converted into electrical signals in order to provide an inputthat can be utilized by a computer, and the transducer that effects thiscon-' version must of course be operating all during the scanningprocess in spite of the fact that the periscope has a combinedrotational and axial motion. The manner in which this is accomplished isexplained hereinafter.

Another and more complex problem is posed by the need for'a very highdegree of precision in the motions of the scanning apparatus. There canbe no play, wobble or eccentricity in the rotation of either the inneror the outer member, even though such rotation is at about 1,000 rpm.The mirror must not be distorted or displaced by centrifugal forces asit rotates. The up and down motion of the inner periscope member must-betruly parallel to the rotation axis. And finally, the optical elementsof the periscope must not whip or how, even though they are spacedsomewhat to one side of the axis about which the periscope revolves andcomprise a relatively slender and resilient shaft.

To insure a high degree of rigidity for the mirror carrying outer member26, its funnel-shaped body member 29 is preferably formed of one pieceof cast iron. The lower tubular or spout portion of that body member isjournaled in a pair of axially spaced apart angular contact ballbearings 30, each comprising a radially inner ring 31 and a radiallyouter ring 32. The radially inner ring 31 has a frustoconical radiallyoutwardly facing ball race surface, while the radially outer ring 32 hasa complementary radially inwardly facing race surface. The two angularcontact ball bearings 30 are arranged with their inner rings 31 remotefrom one another, and therefore the side thrust reaction moments of thetwo bearings are centered at points that are spaced substantialdistances axially outwardly of them, so that the bearings provide goodresistance to tilting of the rotating unit. The inner ring 31 of theupper one of these bearings is engaged against a downwardly facingshoulder 33 on the funnel-shaped member. while the inner ring 31 of thelower bearing is is engaged by a nut 34 that is threaded onto the lowerend of the tubular portion of that member and can be tightened to thepoint where all wobble and vibration is eliminated, thus furtherassuring that the mirror carrying member has true rotational motion.

The mirror carrying member is driven in rotation by an electric motor 36which is mounted to one side of it and which is connected with it bymeans of a belt 38 and a drive pulley 39 on the motor. The best isreceived in a circumferential belt groove 40 around the conical topportion of the mirror carrying member, spaced a small distance above theupper ball bearing 30.

An angle transducer 41 is operatively associated with the mirrorcarrying member to issue signals denoting its position of rotation,which signals are utilized by the computer in its processing of scanninginformation.

An important feature of the scanning apparatus of this invention is acoverlike member 42 which is secured to the top of the funnel-shapedmember and which serves the dual function of providing great rigidity tothe mirror carrying outer member so that it resists mirror displacingdistortion due to centrifugal force, and of steadying the innerperiscope member, as described hereinafter, to prevent it from whippingor wobbling. The coverlike member 42 has a central hublike portion 43through which the inner periscope member 25 extends and has a radiallyextending slot 44 which opens from the hub portion and which is locateddirectly above the mirror, through which the projected image passesdownwardly to the minor.

The inner periscope member 25 comprises a rigid, elongated body member46 which is substantially U-shaped in cross section along most of itslength, to define a slotlike shaft 45 down which light can pass to themirror 27, but which has a tubular lower portion defining a downwardlyopening concentric well 47. The optical elements of the periscopecomprise a fiber optic rod 48 which transmits light along its lengtl.and a small prism or reflector 49 on the top of the fiber optic rodwhich constitutes the eye of the periscope and which receives light fromthe mirror 27 and reflects it down into the rod 48.

The leg portions 50 of the U-shaped body member 46 straddle the mirror27 with a small clearance, as best seen in FIG. 3. The fiber optic rod48 is secured in a small recess or groove in the body member 46 thatopens to the light shaft 45 between its legs 50 and extends lengthwisealong it.

The periscope comprising the body member 46, the prism or reflector 49and the fiber optic rod 48 is moved up and down by means of a reversibleelectric motor 51 which is mounted beneath the rotating members. Theshaft 52 of the motor, which projects upwardly substantiallyconcentrically with the inner and outer members 25 and 26, is threadedalong its length to cooperate with a nut 53 on a yoke 54. Fixed uprightguide rods 55, spaced to opposite sides of the motor, guide the yoke,confining it and the nut to motion up or down, depending upon thedirection of motor rotation. Such motion of the yoke is transmitted tothe periscope by means of a connecting shaft 56 which is substantiallyconcentric with the rotating members and the motor shaft 52 and whichhas its lower end nonrotatably secured to the yoke 54. The upper endportion of the connecting shaft 56 is received in the well 47 in thelower portion of the periscope body and is connected with the periscopebody by means of a suitable axial thrust bearing 57 which provides forrotation of the periscope body relative to the connecting shaft butconstrains the periscope to axial motion with it. The connections of theconnecting shaft 56 with the yoke 54 and with the axial thrust bearing57 comprise spherical joints that compensate for any misalignmentbetween the axis of the motor 51 and that of the rotating inner andouter members.

A position responsive transducer 58 that is associated with the axialdrive mechanism feeds signals to the computer that denote the axialposition of the periscope.

The prism or reflector 49 is necessarily eccentric to the axis aboutwhich the inner and outer members rotate, inasmuch as the mirror extendsacross that axis, and the fiber optic rod 48 must likewise be spacedfrom that axis along most of its length. Near its bottom, however, thefiber optic rod has an offset bend, as at 60, so that its bottom end ison the axis and is located in or near the bearing connection between theperiscope body member 46 and the connecting shaft 56. Another length offiber optic, designated 61, extends through the upper portion oftheconnecting shaft 56 (which is tubular to accommodate it) with its upperend closely adjacent to the bottom end of the rotating fiber optic rod48. The lower nonrotating fiber optic rod extends laterally out of theconnecting shaft through a side aperture in the latter, and over to alight responsive transducer or photoelectric cell 62 which is mounted ina fixed position near the scanning mechahism. The flexibility of thefiber optic accommodates the up and down motion of the connecting shaft56 relative to the transducer 62. lt has been found that light lossesacross the joint between the two lengths offiber optic are notsignificant.

As explained above, it is essential that there be no rotational playbetween the inner and outer members 25 and 26, so that the periscopeaccurately faces the mirror at all times, and that the inner periscopemember, while rotating, move exactly parallel to the rotation axis. Tothis end the periscope body member 46 is formed with certain guidesurfaces or ways that extend along its length, and these cooperate withpairs of surface engaging elements that are carried by the outer member26, one surface engaging element of each pair being on the hub portion43 of the coverlike member 42 and the other being on the lower end ofthe tubular portion of the outer member 26, beneath the lower bearing30.

Specifically, the periscope body member 46 has two track surfaces 64that extend lengthwise of it along its bright portion, at the side ofthe periscope body remote from the mirror, and which lie insubstantially perpendicular planes that are parallel to the axis ofrotation but seen in a cross section, respectively extend to oppositesides of that axis and of a symmetrical plane through that axis. Hencethe track surfaces 64 face obliquely radially outwardly and in oppositecircumferential directions. Special pains are taken with the formationof the track surfaces 64 to insure their accuracy in flatness,straightness and parallelism with the axis of rotation. Hence when thesetrack surfaces are maintained in running engagement with surfaceengaging elements at fixed axially spaced locations on the outer mirrorcarrying member 26, the track surfaces and surface engaging elementscooperate to confine the periscope body 46 to motion exactly parallel tothe axis of rotation. Furthermore, since the track surfaces faceobliquely,

one in the direction of rotation and one in the opposite direction, suchcooperation constrains the periscope body member to rotate with themirror carrying outer member 26.

The cooperation just described is assured by means of yieldingly biasedsurface engaging elements (described hereinafter) on the minor carryingmember which engage two other lengthwise extending steadying surfaces 65on the Y periscope body member, on the leg portions 50 thereof. The

steadying surfaces 65 are spaced substantial distances circumferentiallyfrom the tracks 64, and each preferably faces in a directionsubstantially opposite to one of the tracks 64. While the steadyingsurfaces 65 should be generally straight, flat and parallel to the axisof rotation and hence parallel to the track surfaces 64, it will appearas the description proceeds that the steadying surfaces need not beformed with the same high degree of accuracy as the track surfaces 64.

The several surface engaging elements preferably comprise rollers 66 and67 that are carried by the outer mirror carrying member 26 at thelocations described above. The rollers that cooperate with the tracksurfaces 64 are designated 66, those that engage the steadying surfaces65 are designated 67.

Each of the rollers 66 is joumaled on a shaft 68 that is carried by ablocklike holder 69 which is rigidly but adjustably secured to themirror carrying member 26. These holders are received in rather closelyfitting slots 70 that extend through the wall of the mirror carryingmember, and each holder, in turn, has a slot 71 through it in which theroller rides.

Each holder is secured to the mirror carrying member by means of a pairof bolts 72 and 73 (see F IG. that are respectively spaced above andbelow the roller and extend parallel to its axis. One of these bolts,designated 72, fits closely in a hole through the holder and serves as apivot about which the holder can swing for adjusting motion to carry theroller radially inwardly and outwardly. The other bolt 73, as best seenin FIG. 6, has a conically tapered portion and a cylindric head 74, andthe hole 75 in the holder 69 in which it is engaged is inclined relativeto the axis of roller 66 to extend parallel to the generatrix of thetapered portion at the inner side of the latter, so that the taperedportion is engaging the hole 75 by a line along the hole. The bolt isguided in its inner as well as its outer end by a shoulder and thecylindric head 74 respectively, so that as the bolt 73 is screwed intoits threaded hole in the mirror carrying member, its tapered portioneffects radially inward adjustment of the roller 66. Since each of thetrack surfaces 64 is engaged by a pair of rollers 66, at locationsspaced apart lengthwise of the track surface, it will be evident thatthe adjusting bolts 73 can be employed for aligning the direction of upand down motion of the periscope to be exactly parallel with therotational axis. A suitably formed bay or cutout 76 in the outer surfaceof the member 26 provides for adjusting access to the heads of the bolts73.

The rollers 67 that comprise the surface engaging elementswhich'cooperate with the steadying surfaces 65 engage those surfacesunder yielding bias to thus urge the periscope body member 46 bodily inthe direction to maintain the track surfaces 64 engaged with the rollers66. Furthermore, because the rollers 67 engage the steadying surfaces 65under yielding bias, small departures from true flatness andstraightness in the steadying surfaces are accommodated by bodilyyielding motion of the rollers 67.

The supporting means for each roller 67 comprises a generally U-shapedholder 78 that has its legs straddling the roller and bridged by theshaft 79 of the ro i ler, and a resilient tongue 80, preferably integralwith the U-shaped holder and defined therefrom by a slot 81. The tongue80 projects a substantial distance above the holder proper. A singlebolt 82 extends through the bight portion of the holder and is threadedinto the outer member 26, to provide a pivot about which the holder canswing to carry the roller 67 toward and from the periscope body. Anadjusting screw 83 extends through the upper end portion of the tongue80 and is threaded into the outer member to maintain the upper endportion of the tongue flexed radially inwardly. The adjusting screw 83can be tightened to increase the force by which the roller 67 is urgedagainst the periscope body, or it can be loosened to decrease thebiasing force.

From the foregoing description taken with the accompanying drawings itwill be apparent that this invention provides a spiral reader having amirror which is accurately constrained to rotation in a cone-definingorbit and a periscope which is constrained to rotate with the minor, soas to face the mirror at all times, and which is also compelled, whileso rotating, to move in directions accurately parallel to the axis aboutwhich it and the mirror rotate.

We claim:

1. In a spiral scanner comprising concentrically arranged inner andouter members, the outer member being confined to rotation on an axisand carrying a mirror which extends obliquely to said axis and acrossthe same so as to move in a cone-defining orbit in consequence ofrotation of the outer member, and the inner member comprising aperiscope which extends lengthwise parallel to said axis at one sidethereof and which is moved in opposite directions parallel to said axisfor scanning the mirror, means constraining the inner member to rotatewith the outer member, so that light receiving means of the periscopealways faces the mirror, and to move accurately parallel to said axis,said last named means comprising:

A. means on one of said members defining a pair of elongated tracksurfaces that extend accurately straight and parallel to said axis, saidtrack surfaces being located eccentrically to said axis and lying insubstantially transverse planes which respectively extend to oppositesides of said axis so that one of said track surfaces faces obliquely inone rotational direction and the other faces obliquely in the oppositerotational direction;

B. two pairs of surface engaging elements carried by the other member,one pair for each of said track surfaces, the surface engaging elementsof each pair being at locations fixed on said other member that arespaced apart a substantial distance in the direction of said axis andthe several surface engaging elements being engageable with theirrespective track surfaces to constrain the inner member to rotation withthe outer member and to motion relative to the outer member indirections accurately parallel to said axis; and

C. cooperating means on said members for maintaining a biasing force onthe inner member in a direction transverse to the axis and generallytransverse to said track surfaces to maintain said track engagingelements engaged with said track surfaces, the last mentioned meanscomprising other surface engaging elements carried by one of saidmembers and engaging surface portions of the other member that arecircumferentially spaced from said track surfaces, said other surfaceengaging elements being yieldingly biased to react between the member bywhich they are carried and said surface portions of the other member.

2. The spiral scanner of claim 1, further characterized by each of thesurface engaging elements of said two pairs thereof comprising:

A. a roller; and

B. means joumaling the roller on said other member with the axis of theroller transverse to the first named axis and parallel to the tracksurface engaged by the roller.

3. The spiral scanner of claim 2, further characterized by saidjoumaling means being adjustable in directions generally toward and fromthe first mentioned axis.

4. The spiral scanner of claim 1, further characterized by said surfaceportions circumferentially spaced from the track surfaces being on thesame member with the track surfaces and comprising a pair or elongatedsteadying surfaces, one for each track surface, each of said steadyingsurfaces being spaced a substantial distance circumferentially from itstrack surface and lying in a plane substantially parallel to that of itstrack surface but facing in a direction generally opposite to that inwhich its track surface faces.

5. The spiral scanner of claim 4, wherein said steadying surfaces are onthe inner member, further characterized by said other surface engagingelements comprising:

A. a pair of steadying rollers for each of said steadying surfaces;

B. a holder for each steadying roller upon which the steadying roller isjoumaled for rotation;

C. means securing each holder to the outer member for swinging motion ofthe holder about a pivotal axis which is substantially parallel to thesteadying roller axis and to its steadying surface, transverse to thefirst named axis, and spaced from the steadying roller axis in onedirection lengthwise of the first named axis, so that the steadyingroller is carried bodily in directions generally transverse to the firstmentioned axis in consequence of swinging motion of the holder;

D. a resilient tongue for each holder having one end anchored to theholder and having its other end spaced a substantial distance from saidpivotal axis; and

E. cooperating means on the outer member and on said other end portionof each tongue for adjustably maintaining said other end portion of thetongue in a position such that the tongue is flexed to apply a desiredbiasing force to the holder by which the holder is urged to swing aboutthe pivot axis in the direction generally toward the first mentionedaxis.

6. Means for scanning a projected image in a spiral path,

comprising:

A. a substantially funnel-shaped mirror-carrying member having;

1. a conical upper portion, and 2. a tubular lower portion;

B. means mounting the mirror-carrying member for rotation about itsaxis;

C. an elongated plane mirror secured to the inner surface of the conicalupper portion of the mirror-carrying member and extending lengthwisetherealong at an upward inclination to the axis but with its lowerportion extending across the axis, said mirror being thus arranged tomove in a cone-defining orbit in consequence or rotation of themirror-carrying member;

D. an elongated periscope body member received in the mirror-carryingmember for rotation therewith and for lengthwise motion in oppositeaxial directions relative thereto, said periscope body member having asubstantially U-shaped cross section with its legs straddling the mirrorand defining between them a slotlike light shaft that extends downwardlyto the mirror;

E. means fixed to the periscope body member for transmitting lightlengthwise therealong, said means providing a light receiving surfaceoptically aligned with the mirror;

F. a rigid coverlike member secured to the top of the conical upperportion of the mirror-carrying member to prevent distortion of themirror under the effects of centrifugal force, said coverlike memberhaving;

1. a central hublike portion through which the periscope body memberprojects upwardly, and

2. a slot opening radially from said hublike portion and registeringwith the light shaft in the periscope body member.

G. means on the periscope body member defining circumferentially spacedapart guide surfaces which extend axially therealong and which faceobliquely to planes lying on the axis of rotation;

H. surfaces engaging elements on said hublike portion engaging saidguide surfaces; and

1. other surface engaging elements on the lower end of the tubularportion of the mirror-carrying member, also engaging said guide surfacesand cooperating with the first mentioned surface engaging elements toconstrain the periscope member to rotate with the mirror-carrying memberand to move lengthwise relative thereto in directions parallel to theaxis of rotation.

7. The scanning means of claim 6, further characterized by:

A. two of said guide surfaces being master surfaces on the bight portionof the periscope body member, at the side thereof remote from the lightshaft, which face in opposite obliquely circumferential directions andare accurately straight and parallel to the axis of rotation;

B. there being a guide surface also on the outer surface of each of theleg portions of the periscope body member, one for each master surfacebut facing in substantially the opposite direction;

C. the first mentioned surface engaging elements comprisl. four rollers,one for each of said guide surfaces,

2. means mounting the two of said rollers that engage the master guidesurfaces on said hub like portion, for rotation on axes that are fixableat different positions of adjustment generally toward and from the axisof rotatron,

3. means rotatably mounting the other two of said rollers on saidhublike portion for bodily motion generally toward and from the mastersurfaces, and

4. means reacting between said hublike portion and said other tworollers to bias the latter in the direction toward the periscope bodymember to thereby maintain the master surfaces engaged with theirrespective rollers; and

D. said other surface engaging elements comprising;

1. four rollers, one for each of said guide surfaces,

2. means mounting the two of said last mentioned four rollers thatengage the master guide surfaces on the mirror-carrying member forrotation on axes that are fixable at different positions of adjustmentgenerally toward and from the axis of rotation,

. means rotatably mounting the other two of the last mentioned fourrollers on the mirror-carrying member for bodily motion generally towardand from the master surfaces, and

4. means reacting between the mirror-carrying member and the lastmentioned other two rollers to bias the latter in the direction towardthe periscope body member, to thereby maintain the master surfacesengaged with their respective rollers.

8. ln a spiral scanner comprising concentrically arranged inner andouter members, the outer member being confined to rotation on an axisand carrying an elongated mirror which extends obliquely to said axisand across the same and faces obliquely toward and along said axis so asto define a reflective cone in consequence of rotation of the outermember, and the inner member comprising a periscope which extendslengthwise parallel to said axis at one side thereof, means constrainingthe inner member to rotate with the outer member, so that thelight-receiving means of the periscope always faces the mirror, andconstraining the inner member to move lengthwise accurately parallel tosaid axis for scanning of the mirror by the periscope, the lastmentioned means comprising:

A. means on the inner member defining a pair of elongated track surfacesthat extend accurately straight and parallel to said axis, said tracksurfaces being located eccentrically to said axis and lying insubstantially transverse planes which respectively extend to oppositesides of said axis so that one of said track surfaces faces obliquely inthe direction of rotation and the other faces obliquely in the oppositedirection;

B. means on the inner member defining a pair of elongated steadyingsurfaces, one for each track surface, each of said steadying surfacesbeing spaced a substantial distance circumferentially from its tracksurface and being substantially parallel to its track surface but facingin a direction generally opposite to that in which its track surfacefaces;

C. a first two pairs of rollers on the outer member, one pair for eachof said track surfaces, the rollers of each pair having journals fixedon the outer member at locations that are spaced apart a substantialdistance in the direction of said axis, said rollers being rollinglyengageal2 ble with their track surfaces to constrain the inner 9. Thespiral scanner of claim 8 wherein the outer member member to rotationwith the outer member and to motion comprises a substantiallyfunnel-shaped body with a conical relative to the outer member indirections accurately upper portion and a tubular lower portion, andwherein the parallel tosaid axis; inner member comprises a periscopebody member having a D. a second two pairs of rollers. a pair for eachof said U-shaped cross section, the legs of which straddle the mirrorsteadying surfaces; and and define a slotlike light shaft that extendsdownwardly to the E. means freely rotatably mounting each of said e nd wmirror, further characterized by a cover like member on the pairs ofrollers on the outer member with the rollers of P of i fuhhel'shaped y Freinforce the same and h pair spaced apart in h direction f said axis,Said prevent distortion of the mirror, said coverlike member having lastnamed means comprising biasing means by which the i0 14 a hubhke Roniohthrough which the Periscope y rollers of said second two pairs aremaintained engaged member P J and "P which are mounted one of with theirrespective steadying surfaces under yielding each ofsaiqtwo P i A biasby which the tone of the first two pairs arc main 2. a slot openingradially from said hubllke portion and retained in firm rollingengagement with their respective gistefing with thcligm shaft)admimghuheretotrack surfaces. is

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 572383 Dated margh 3Q 1911 Invent Stem Nordlund It is certified that errorappears in the above-identified patem and that said Letters Patent arehereby corrected as shown below:

Column 2 line 66: "the" should be --They-- Column 3 line 23: After"television" insert ---receiver 16 that is connected with thetelevision-- Column 3 line 1&2: "aligne-ment" should read --align-ment"Colunm 4 line 27: I delete "a" after --more-- Column 5 line 35 change"best" to --belt-- Column 8 line 70 "or" should be --of-- Column 9 line41 change "or" to --of- Column 9 line 61 change the "period" to a---comma Column 9- line 66 change "surfaces" to --surface-- Column 12line 12 "roller" should be --rollers- Signed and sealed this 31st day ofAugust 1971.

(SEAL) Attest:

EDWARD M.FIETCHERa ROBERT GOTTSCHALK Attosting f -i Acting Commissionerof P 1 FORM P0-105O (10-59) llnfihmnLA-HP a!

1. In a spiral scanner comprising concentricAlly arranged inner and outer members, the outer member being confined to rotation on an axis and carrying a mirror which extends obliquely to said axis and across the same so as to move in a cone-defining orbit in consequence of rotation of the outer member, and the inner member comprising a periscope which extends lengthwise parallel to said axis at one side thereof and which is moved in opposite directions parallel to said axis for scanning the mirror, means constraining the inner member to rotate with the outer member, so that light receiving means of the periscope always faces the mirror, and to move accurately parallel to said axis, said last named means comprising: A. means on one of said members defining a pair of elongated track surfaces that extend accurately straight and parallel to said axis, said track surfaces being located eccentrically to said axis and lying in substantially transverse planes which respectively extend to opposite sides of said axis so that one of said track surfaces faces obliquely in one rotational direction and the other faces obliquely in the opposite rotational direction; B. two pairs of surface engaging elements carried by the other member, one pair for each of said track surfaces, the surface engaging elements of each pair being at locations fixed on said other member that are spaced apart a substantial distance in the direction of said axis and the several surface engaging elements being engageable with their respective track surfaces to constrain the inner member to rotation with the outer member and to motion relative to the outer member in directions accurately parallel to said axis; and C. cooperating means on said members for maintaining a biasing force on the inner member in a direction transverse to the axis and generally transverse to said track surfaces to maintain said track engaging elements engaged with said track surfaces, the last mentioned means comprising other surface engaging elements carried by one of said members and engaging surface portions of the other member that are circumferentially spaced from said track surfaces, said other surface engaging elements being yieldingly biased to react between the member by which they are carried and said surface portions of the other member.
 2. a slot opening radially from said hublike portion and registering with the light shaft to admit light thereto.
 2. The spiral scanner of claim 1, further characterized by each of the surface engaging elements of said two pairs thereof comprising: A. a roller; and B. means journaling the roller on said other member with the axis of the roller transverse to the first named axis and parallel to the track surface engaged by the roller.
 2. means mounting the two of said last mentioned four rollers that engage the master guide surfaces on the mirror-carrying member for rotation on axes that are fixable at different positions of adjustment generally toward and from the axis of rotation,
 2. means mounting the two of said rollers that engage the master guide surfaces on said hub like portion, for rotation on axes that are fixable at different positions of adjustment generally toward and from the axis of rotation,
 2. a slot opening radially from said hublike portion and registering with the light shaft in the periscope body member. G. means on the periscope body member defining circumferentially spaced apart guide surfaces which extend axially therealong and which face obliquely to planes lying on the axis of rotation; H. surfaces engaging elements on said hublike portion engaging said guide surfaces; and I. other surface engaging elements on the lower end of the tubular portion of the mirror-carrying member, also engaging said guide surfaces and cooperating with the first mentioned surface engaging elements to constrain the periscope member to rotate with the mirror-carrying member and to move lengthwise relative thereto in directions parallel to the axis of rotation.
 2. a tubular lower portion; B. means mounting the mirror-carrying member for rotation about its axis; C. an elongated plane mirror secured to the inner surface of the conical upper portion of the mirror-carrying member and extending lengthwise therealong at an upward inclination to the axis but with its lower portion extending across the axis, said mirror being thus arranged to move in a cone-defining orbit in consequence or rotation of the mirror-carrying member; D. an elongated periscope body member received in the mirror-carrying member for rotation therewith and for lengthwise motion in opposite axial directions relative thereto, said periscope body member having a substantially U-shaped cross section with its legs straddling the mirror and defining between them a slotlike light shaft that extends downwardly to the mirror; E. means fixed to the periscope body member for transmitting light lengthwise therealong, said means providing a light receiving surface optically aligned with the mirror; F. a rigid coverlike member secured to the top of the conical upper portion of the mirror-carrying member to prevent distortion of the mirror under the effects of centrifugal force, said coverlike member having;
 3. means rotatably mounting the other two of the last mentioned four rollers on the mirror-carrying member for bodily motion generally toward and from the master surfaces, and
 3. The spiral scanner of claim 2, further characterized by said journaling means being adjustable in directions generally toward and from the first mentioned axis.
 3. means rotatably mounting the other two of said rollers on saId hublike portion for bodily motion generally toward and from the master surfaces, and
 4. The spiral scanner of claim 1, further characterized by said surface portions circumferentially spaced from the track surfaces being on the same member with the track surfaces and comprising a pair or elongated steadying surfaces, one for each track surface, each of said steadying surfaces being spaced a substantial distance circumferentially from its track surface and lying in a plane substantially parallel to that of its track surface but facing in a direction generally opposite to that in which its track surface faces.
 4. means reacting between the mirror-carrying member and the last mentioned other two rollers to bias the latter in the direction toward the periscope body member, to thereby maintain the master surfaces engaged with their respective rollers.
 4. means reacting between said hublike portion and said other two rollers to bias the latter in the direction toward the periscope body member to thereby maintain the master surfaces engaged with their respective rollers; and D. said other surface engaging elements comprising;
 5. The spiral scanner of claim 4, wherein said steadying surfaces are on the inner member, further characterized by said other surface engaging elements comprising: A. a pair of steadying rollers for each of said steadying surfaces; B. a holder for each steadying roller upon which the steadying roller is journaled for rotation; C. means securing each holder to the outer member for swinging motion of the holder about a pivotal axis which is substantially parallel to the steadying roller axis and to its steadying surface, transverse to the first named axis, and spaced from the steadying roller axis in one direction lengthwise of the first named axis, so that the Steadying roller is carried bodily in directions generally transverse to the first mentioned axis in consequence of swinging motion of the holder; D. a resilient tongue for each holder having one end anchored to the holder and having its other end spaced a substantial distance from said pivotal axis; and E. cooperating means on the outer member and on said other end portion of each tongue for adjustably maintaining said other end portion of the tongue in a position such that the tongue is flexed to apply a desired biasing force to the holder by which the holder is urged to swing about the pivot axis in the direction generally toward the first mentioned axis.
 6. Means for scanning a projected image in a spiral path, comprising: A. a substantially funnel-shaped mirror-carrying member having;
 7. The scanning means of claim 6, further characterized by: A. two of said guide surfaces being master surfaces on the bight portion of the periscope body member, at the side thereof remote from the light shaft, which face in opposite obliquely circumferential directions and are accurately straight and parallel to the axis of rotation; B. there being a guide surface also on the outer surface of each of the leg portions of the periscope body member, one for each master surface but facing in substantially the opposite direction; C. the first mentioned surface engaging elements comprising:
 8. In a spiral scanner comprising concentrically arranged inner and outer members, the outer member being confined to rotation on an axis and carrying an elongated mirror which extends obliquely to said axis and across the same and faces obliquely toward and along said axis so as to define a reflective cone in consequence of rotation of the outer member, and the inner member comprising a periscope which extends lengthwise parallel to said axis at one side thereof, means constraining the inner member to rotate with the outer member, so that the light-receiving means of the periscope always faces the mirror, and constraining the inner member to move lengthwise accurately parallel to said axis for scanning of the mirror by the periscope, the last mentioned means comprising: A. means on the inner member defining a pair of elongated track surfaces that extend accurately straight and parallel to said axis, said track surfaces being located eccentrically to said axis and lying in substantially transverse planes which respectively extend to opposite sides of said axis so that one of said track surfaces faces obliquely in the direction of rotation and the other faces obliquely in the opposite direction; B. means on the inner member defining a pair of elongated steadying surfaces, one for each track surface, each of said steadying surfaces being spaced a substantial distance circumferentially from its track surface and being substantially parallel to its track surface but facing in a direction generally opposite to that in which its track surface faces; C. a first two pairs of rollers on the outer member, one pair for each of said track surfaces, the rollers of each pair having journals fixed on the outer member at locations that are spaced apart a substantial distance in the direction of said axis, said rollers being rollingly engageable with their track surfaces to constrain the inner member to rotation with the outer member and to motion relative to the outer member in directions accurately parallel to said axis; D. a second two pairs of rollers, a pair for each of said steadying surfaces; and E. means freely rotatably mounting each of said second two pairs of rollers on the outer member with the rollers of each pair spaced apart in the direction of said axis, said last named means comprising biasing means by which the rollers of said second two pairs are maintained engaged with their respective steadying surfaces under yielding bias by which the rollers of the first two pairs are maintained in firm rolling engagement with their respective track surfaces.
 9. The spiral scanner of claim 8 wherein the outer member comprises a substantially funnel-shaped body with a conical upper portion and a tubular lower portion, and wherein the inner member comprises a periscope body member having a U-shaped cross seCtion, the legs of which straddle the mirror and define a slotlike light shaft that extends downwardly to the mirror, further characterized by a cover like member on the top of said funnel-shaped body to reinforce the same and prevent distortion of the mirror, said coverlike member having 